The invention concerns the removal of dead tissue from a wound, and more particularly, a bandage that promotes the removal of dead tissue by substances that the body itself produces.
Chronic wounds are a common aliment, afflicting over 5 million people annually in this country. The majority of chronic wounds are caused by a local or generalized vascular insufficiency that reduces blood flow to the skin and subcutaneous tissue. The most common type of chronic wounds include: pressure ulcers (decubiti, or xe2x80x9cbed soresxe2x80x9d); diabetic ulcers; arterial ulcers; venous ulcers; or a combination of these. Chronic wounds are full-thickness skin injuries that may be very large and that may persist for months or years.
The treatment of chronic wounds presents may challenges. First, chronic wounds frequently exude large volumes of fluid. In the case of venous leg ulcers or pressure ulcers, this fluid may primarily be a serous transudate consisting of plasma and interstitial fluid. In the case of an infected or heavily colonized wound or a wound with necrotic (dead) tissue, the fluid will contain many white blood cells, cellular debris, and toxic cellular metabolic waste products. Such fluid is commonly denominated as xe2x80x9cexudatexe2x80x9d or xe2x80x9cpusxe2x80x9d.
Historically, the philosophy of wound management has encouraged drying a wound. To promote drying, a wound would be covered with a simple absorbent gauze, or left open to the air to dry. At times, heat may have been applied to the wound to enhance drying. It is now recognized that drying the wound can actually inhibit healing.
Currently, the goal of wound management is to keep a wound moist. This may be accomplished by trapping exudate or transudate in a wound bed under a substantially fluid-impermeable bandage. This practice avoids drying a wound, but leads to a new problem. In this regard, larger amounts of fluid from moderate or heavily exudating wounds may result in a pool of trapped fluid under the bandage. This pool of fluid is in constant contact with the wound and the peri-wound skin, which is a margin of skin that surrounds and abuts the wound. As a result, the wound and peri-wound tissues are constantly wet, which can lead to maceration and further damage. Additionally, the fluid contains cellular debris and metabolic waste products that may be toxic to the living tissue of the wound bed and peri-wound. The toxicity of the fluid may retard wound healing and, indeed, may damage healthy peri-wound tissue and already healed wound tissue.
Consequently, there is a need for a device that maintains an environment of high humidity over a wound in order to prevent evaporative drying of the wound while, at the same time, managing the excess fluid to keep it away from the peri-wound skin and the wound bed. In short, there is a need for a device that will keep a wound area humid, but not wet.
One significant advantage to be gained by use of such a device would be optimization of autolytic debridement. Autolytic debridement denotes the body""s natural ability to break down dead tissue, thereby continuously cleaning a wound so that new skin cells can grow to fill and cover the wound, thereby promoting its healing. In this regard, xe2x80x9cautolyticxe2x80x9d refers to the destruction of dead tissue by agents produced by the body. xe2x80x9cDebridementxe2x80x9d is the removal of dead cells or tissue from a wound. Autolytic debridement is therefore the breaking down and removal of dead tissue from a wound by substances and processes that are natural to the body. This function is carried out by white blood cells generally known as phagocytes, and by a variety of enzymes. In the process the phagocytes die and add to the cellular debris of the necrotic tissue in the exudate fluid. The exudate fluid flows away from the wound, thereby removing the dead cells and other debris. Autolytic debridement under prior art wound bandages is usually ineffective at cleaning wounds because the exudate fluid collects and pools in the wound. Clinicians must frequently intervene by resorting to repeated surgical debridement in order to clean necrotic tissue from a wound. There is a need therefore to support and enhance autolytic debridement by removing exudate with its toxic waste by-products from the wound area.
Since autolytic debridement is an autogenic process, driven by the functioning of body systems, it is affected by temperature. In this regard, hypothermia is known to slow or even stop cellular functions, immune system functions, enzyme reactions, and biochemical processes. Effective phagocytosis requires an active immune system, active cellular functions, and rapid enzyme and biochemical reactions. Many wounds, because of their locations on body limbs, are hypothermic. The cool environment of these wounds slows down the process of autolytic debridement, extending the time required for healing.
Accordingly, the need for a device to keep a wound area humid, but not wet, is compounded by the need for the device to enhance autolytic debridement by carrying exudate away from the wound and keeping the wound warm.
We have invented a device that meets these needs by maintaining a warm, humid environment at and over a wound and by collecting exudate fluid at a location away from the wound and peri-wound area, thereby enabling the process of autolytic debridement.
Our invention embraces at least two components. First is a non-contact bandage with an outer shell that creates an enclosure over and about a wound, that does not touch the wound. The enclosure includes an adhesive attachment means that adhesively attaches the bandage to the skin around the wound, forming a chamber that is substantially sealed over the wound. Second, a fluid absorbent material is placed inside the chamber, away from the wound to absorb fluid from the wound.
More particularly, the invention is a bandage for autolytic debridement that includes a fluid-impermeable enclosure having a sidewall forming a margin that defines an opening, and a skin-facing surface extending beyond the margin away from the opening. An attachment means is disposed on the skin-facing surface for attaching the enclosure to skin to create a closed, fluid-impermeable chamber over a wound, substantially without contacting the wound. A fluid absorbent material is disposed in the fluid-impermeable enclosure substantially at or near the margin and out of the opening.
Significant advantages are realized when our bandage for autolytic debridement is used. In forming a closed, fluid-impermeable chamber over a wound, our bandage maintains an environment of almost 100% relative humidity over the wound, thereby preventing evaporative drying of the wound. The enclosure and its humid atmosphere tend to retain warmth or heat, thereby raising the temperature of the tissues in the peri-wound area and the wound bed to a near-normothermic level, that is a level in the range of about 36xc2x0 C. to about 38xc2x0 C. Dispelling hypothermia in these tissues enhances the physiologic processes that drive autolytic debridement. The collection of exudate fluid at a location away from the wound bed reduces or eliminates pooling on the wound bed and peri-wound area, which tends to accelerate autolytic debridement and promote wound healing. Finally, since the bandage does not touch the wound, its removal does not tear away growing cells at the margin and in the bed of a wound. Lifting or removal of our bandage will not cause bleeding in the wound or morbid damage to growing cells.
These advantages and other profitable characteristics of our bandage will become apparent when the following detailed description is read with reference to the below-described drawings.